The present disclosure relates to display of digital documents on computer devices, and more particularly to display of page numbers.
Digital documents may be data files that represent a document conventionally printed on paper. For example, a common digital document format is the portable document format (PDF). The PDF format includes two techniques for representing page numbers of the document: a mandatory sequential numerical page number and an optional page label defined by a tree structure.
Many real-world documents (e.g., books, newspapers, legal documents, and technical specifications) use numbering systems more complex than a sequential numbers. As a simple example, a book may include an unnumbered inner cover or title page followed by sequential page numbers. As another example, a document may include a table of contents numbered with roman numerals and content pages sequentially numbered. When such documents are represented in a digital document such as a PDF, the PDF sequential numbering (which begins from “1” at the first page) may not align with the numbering system included in the pages of the document (which, for example, may include Roman numerals for the first 8 pages, so what is actually “i” will show up as page 1, and what is actually 1 will show up as page 9). A conventional PDF viewer application may display the PDF sequential number for a displayed page, which may confuse a user and make navigation within the document difficult.
Although the PDF page label system provides an alternative numbering system that may be used to represent many document page numbers, PDF page labels are conventionally specified by a document author. Many document authors, however, specify no page labels or specify page labels that include the same issues as sequential page numbers. Additionally, if a PDF document is manipulated, embedded page labels may be automatically deleted or may become incorrect.
Thus, there is a need in the art for improvements in display of page numbers for digital documents.